With the development of mobile communications, users have higher and higher requirements on the capacity of a communication system. One of the effective methods of effectively increasing the system capacity at low cost is using a multiple-beam antenna to increase sectors for an existing network. Generally, the multiple-beam antenna normally includes a beamforming network and an antenna array connected to the network, where the beamforming network is capable of receiving at least two paths of input signals through a base station signal port, performing phase and amplitude adjustment for the input signals to generate output signals having a preset phase and amplitude, and then outputting the output signals to the antenna array through an antenna signal port; and the antenna array is configured to transmit the output signals by using the beam corresponding to the output signals. Normally, each path of signals corresponds to one beam after the foregoing adjustment is performed. Therefore, the antenna is capable of generating at least two different beams to increase the system capacity.
A typical application structure for the beamforming network of the antenna in the prior art is a Butler (Butler) matrix. For example, the Butler matrix may include six hybrid couplers and four phase shift apparatus, where the six hybrid couplers are categorized into three layers with two hybrid couplers on each layer, and a phase shift apparatus is set between two layers of hybrid couplers to delay output signals of the hybrid couplers for a specific phase and then output the output signals. The Butler matrix may eventually output the output signals having a preset phase and amplitude, and send the output signals to an antenna array. For example, assume that the matrix has four output ports which are respectively connected to four antenna arrays, after input signals are processed by the Butler matrix, the phases of output signals of adjacent output ports may have a 90-degree difference in turn, and the amplitudes of the four paths of output signals are distributed in 0.414:1:1:0.414.
The beamforming network in the foregoing antenna uses too many hybrid couplers and phase shift apparatuses, and the hybrid couplers and phase shift apparatuses are connected by using complex structures, resulting in high cost of antennas at present.